[Radio button] Fixed sample code in documentation
[Radio button] Fixed sample code in documentation

Resolves https://github.com/material-components/material-components-android/pull/1965

GIT_ORIGIN_REV_ID=e0cb63ede7a16d244232a91b82f2109bbcef73ec
PiperOrigin-RevId: 350592926

material-components/material-components-android